A couple of B7971 board questions
- I looked for answers in the files section, but didn't see the info. So
I'm posting here.
First, the assembly instructions say to see Figure 2 for a list of
resistor values for various HV supply voltages, but there's no Figure 2
in the document (just 1 and 3). Does anyone know the value for a 180V
Second, I'd like to use the preferred connectors for the boards. Onno's
site says "including high quality AMP connectors" when purchasing an
assembled board. As I just bought bare boards, what connector are
people using (for both the board and the mating cable end)?
- I just finished building my Smartsockets and got them fired up yesterday - :)
Wow, B7971's are *big*..
I just used a link for R31, since I'm running at 170v.
If your power supply is not adjustable, then the accurate way would be to
meter the current and choose a resistor accordingly, although I dont
quite "get it" as to how a single anode resistor can be accurate if an
unknown number of cathodes are illuminating.
AMP is a brand of connectors.. there are many different styles in their range.
I just used the ones my local electronics shop had, which are a bit tedious
to assemble since each pin requires seperate crimping and insertion into the
They had another style that worked with Ribbon cable and a little tool
to "punch-down" the wires into the top of the connector (an IDC - insulation
displacement connector), but they didnt have any of the appropriate punch
tools in stock, so I couldnt use them.. after spending hours making the 36+
crimp connections, I'd choose the quicker-to-assemble IDC models and get the
tool next time unless you are only making a few sockets.
Now to figure out Pythons string-slicing capabilities to write some funky
display programs for them.. I've got as far as scrolling "Testing" back and
forwards - :)
On Mon, 28 Apr 2008 01:34:58 pm tkennedyny wrote:
> I looked for answers in the files section, but didn't see the info. So
> I'm posting here.
> First, the assembly instructions say to see Figure 2 for a list of
> resistor values for various HV supply voltages, but there's no Figure 2
> in the document (just 1 and 3). Does anyone know the value for a 180V
> Second, I'd like to use the preferred connectors for the boards. Onno's
> site says "including high quality AMP connectors" when purchasing an
> assembled board. As I just bought bare boards, what connector are
> people using (for both the board and the mating cable end)?
- Hi there.
Do any of you guys fancy posting some pictures? I fancy a kit myself...
On 28 Apr 2008, at 04:57, Brett Paulin wrote:
> I just finished building my Smartsockets and got them fired up
> yesterday - :)
> Wow, B7971's are *big*..
- On 28 Apr 2008, at 10:35, Ray Fenwick wrote:
> Hi there.Well Ray, the boards do what they say they will do. They are good! I
> Do any of you guys fancy posting some pictures? I fancy a kit
> Many thanks
used crimp connectors from D sockets for my tubes, soldered to the
smartsocket PCBs. They worked just fine.
I just uploaded my files for my clock to the files section, in a
folder called John's clock. Pictures of the built unit are in the
I have uploaded:
1] My very simple circuit diagram. I knocked it up in no time on
Veroboard. It's up to you how you generate your high voltage for the
tubes. I used the back-to-back twin transformer method.
2] A list of four letter words to burn to i2C EEPROM - a 24AA512.
This is a list of all the allowable English four letter words in the
board game of 'Scrabble'. No I haven't heard of a lot of them either.
3,539 four letter words in total. Yes the rude ones are all in there.
There is no profanity setting, just switch the clock off when the
prurient are visiting. My sister is an ordained minister and so far
it has failed to say anything abusive in her presence, thank dog. At
other times it has been hilarious when it says something seemingly
3] PicBasic code for the clock (there are some comments in there of
how it works)
4] Hex code to burn a 16F628a PIC for the clock.
If anyone wants to build this clock, I can supply a burned PIC and
The clock is not 100% as I would like it and I keep meaning to
revisit it and tidy up the editing etc., and add some UDCs (user
defined characters) and animations, which is why I haven't posted my
gubbins before. When I do this I will upload new code and make it
In operation the clock tells the time every minute for a while. The
rest of the time it is displaying random 4 letter words. The fade
effect changes every now and again. I can't remember just when, but
look in the PicBasic code and you can probably work it out.
> Do any of you guys fancy posting some pictures?OK, You asked for it.. Family Photo :) - I hope noone minds attachments on
> I fancy a kit myself... Many thanks
the mailing list
- B7971's in Smartsockets, IN4, IN8, IN12 in SmartNixie-Socket, IN13 Tube
Sorry about the low-res, its a camera-phone. I'll make some better ones when
they get nice cases to live in and are worth photographing :)
Kits arent usually worth it for low volume producers - Smartsockets arent too
hard to source the parts for yourself - Building them took more time than
finding the parts.
Onno has the Micros, PCB, Sockets and Tubes available here
which just leaves you the resistors, transistors and connectors to find.
My Liquid Neon Tubes arrived today, wait till you see what I have in mind for
the next Smartsocket ! :)
The connectors and headers i'm using right now came from Farnell.
Header: 9731636 MOLEX 22-05-7058
Connect: 146256 MOLEX 22-01-2055
Pins: 9773789 MOLEX 08-50-0032
- --- In email@example.com, Brett Paulin <yahoogroups@...>
>yesterday - :)
> I just finished building my Smartsockets and got them fired up
> Wow, B7971's are *big*..be to
> I just used a link for R31, since I'm running at 170v.
> If your power supply is not adjustable, then the accurate way would
> meter the current and choose a resistor accordingly, although Idont
> quite "get it" as to how a single anode resistor can be accurate ifan
> unknown number of cathodes are illuminating.Hello,
If the datasheet for the B7971's is to believed then the different
lengths of the cathodes lend themselves very well to approporiately
chosen resistors in the standard values series.
Not sure if that was the intention or if that's how it worked out,
but to clarify , you should choose the resistor value for the cathode
resistors to get you as close as possible to the desired current
values for your device , ZM1350 or B7971. However you may be slightly
out even then , and the voltage from the supply a little high still,
in which case adding a small amount of anode resistance, used just to
trim the final voltage, can be used. It was probably overkill on my
part to include it, but I felt that for all the time and effort it
takes to be able to quickly add a bit of resitance or possibly even a
fuse it was worth including.
In a test I did with a 200V supply I found that when comparing one
tube with the the resistors for 170V plus a small anode resitor,
against a tube with reistors for 200V and no anode resitor, there was
only a very slight difference in the apparent brightness of the
cathodes regardless of the number which were being actived. Flat
orange is a difficult colour to judge brightness of and radiant
orange is very difficult to judge in close relative terms.
Basically what I wanted to say was that the anode reistor is moreof a
luxury and for added protection. A small reduction in cathode current
can create a much longer tube lifetime in the right circumstances and
so I opted to have one, just in case anyone needed to set the
voltages from a non-adjustable supply which demand odd valued
As long as the bulk of the current limiting is being done with the
cathode resistors any anode resistance you need to choose to further
limit the current for one cathode will not produce a very noticeable
effect when all cathodes are activated